The effect of cyanide intoxication on hepatic rhodanese kinetics.

1. Results of studies on the kinetics of hepatic rhodanese and the effects of S-adenosyl-L-methionine (SAM) on these kinetic parameters in cyanide-treated and non-treated mice are reported here. 2. The enzyme exhibited typical Michaelis-Menten behaviour with cyanide inhibition at concentrations higher than 50 mM. Km values of 4.74 and 0.85 mM were obtained for thiosulphate and cyanide, respectively, in control mice. 3. These results stress the biological importance of the rhodanese reaction for cyanide detoxification. 4. Km values were not significantly modified when the animals were intoxicated with a lethal (20 mg/kg) or a non-lethal (4 mg/kg) dose of cyanide. 5. SAM treatment either in control or in cyanide-poisoned animals doubled the Km's for cyanide.